1 /* Microsoft Reference Implementation for TPM 2.0
2 *
3 * The copyright in this software is being made available under the BSD License,
4 * included below. This software may be subject to other third party and
5 * contributor rights, including patent rights, and no such rights are granted
6 * under this license.
7 *
8 * Copyright (c) Microsoft Corporation
9 *
10 * All rights reserved.
11 *
12 * BSD License
13 *
14 * Redistribution and use in source and binary forms, with or without modification,
15 * are permitted provided that the following conditions are met:
16 *
17 * Redistributions of source code must retain the above copyright notice, this list
18 * of conditions and the following disclaimer.
19 *
20 * Redistributions in binary form must reproduce the above copyright notice, this
21 * list of conditions and the following disclaimer in the documentation and/or other
22 * materials provided with the distribution.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ""AS IS""
25 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
27 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
28 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
29 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
30 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
31 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
32 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
33 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
34 */
35
36 //** Introduction
37 // In some implementations of the TPM, the hardware can provide a secret
38 // value to the TPM. This secret value is statistically unique to the
39 // instance of the TPM. Typical uses of this value are to provide
40 // personalization to the random number generation and as a shared secret
41 // between the TPM and the manufacturer.
42
43 //** Includes
44 #include "PlatformData.h"
45 #include "Platform_fp.h"
46 #include <wolfssl/wolfcrypt/sha512.h>
47
48 char tpmUnique[WC_SHA512_DIGEST_SIZE] = {0};
49
50 //** _plat__GetUnique()
51 // This function is used to access the platform-specific unique value.
52 // This function places the unique value in the provided buffer ('b')
53 // and returns the number of bytes transferred. The function will not
54 // copy more data than 'bSize'.
55 // NOTE: If a platform unique value has unequal distribution of uniqueness
56 // and 'bSize' is smaller than the size of the unique value, the 'bSize'
57 // portion with the most uniqueness should be returned.
58 LIB_EXPORT uint32_t
_plat__GetUnique(uint32_t which,uint32_t bSize,unsigned char * b)59 _plat__GetUnique(
60 uint32_t which, // authorities (0) or details
61 uint32_t bSize, // size of the buffer
62 unsigned char *b // output buffer
63 )
64 {
65 const char *from = tpmUnique;
66 uint32_t retVal = 0;
67
68 if(which == 0) // the authorities value
69 {
70 for(retVal = 0; retVal < bSize; retVal++)
71 {
72 *b++ = *from++;
73 }
74 }
75 else
76 {
77 #define uSize sizeof(tpmUnique)
78 b = &b[((bSize < uSize) ? bSize : uSize) - 1];
79 for(retVal = 0; retVal < bSize; retVal++)
80 {
81 *b-- = *from++;
82 }
83 }
84 return retVal;
85 }
86